Subcutaneous immunotherapy for tree pollen allergy with a preparation with optimised allergen aluminium hydroxide ratio: An open label observational study investigating tolerability and effectiveness in the routine use in daily practise

Background: For subcutaneous immunotherapy (SCIT) allergens usually are adsorbed to aluminium hydroxide (alum) for slow allergen release (depot effect). In addition alum also acts as an adjuvant that enhances the immunological effect. Therefore, a SCIT product with an optimised allergen/alum ratio allows reducing the maximum dose applied for maintenance therapy and shorter up-dosing schedules. In this open observational study the tolerability and effectiveness in the routine use in daily practise of a product with an optimised allergen/alum ratio with a five-injection up-dosing schedule was investigated.

Methods: Patients with rhinoconjunctivitis with/without asthma induced by birch/tree pollen were treated with a SCIT depot preparation (Birch or Tree-Mix, AVANZ, ALK-Abelló, Hørsholm, Denmark) containing 15% of the allergen content and 50% of the alum content compared with the widely used ALK allergen product for SCIT (Alutard SQ, ALK-Abellò, Hørsholm, Denmark). Therapy was initiated by up-dosing with 5 injections (300, 600, 3.000, 6.000, 15.000 SQ+) in weekly intervals and was continued by maintenance injections of 15.000 SQ+ with 14 and 28 days intervals.

Results: In total 409 patients were documented (Birch: 81, Tree Mix: 328 patients). The effectiveness of the treatment was rated as good or very good by 88.2% of the patients (Birch 85.1%, Tree-Mix 88.8%) and 90.7% by the investigators (Birch 87.2%, Tree-Mix 91.5%). Adverse events were in general mild to moderate local reactions and occurred in 22.7% of the patients mostly at up-dosing (18.8% of patients). Serious adverse events were reported in 5 patients (1.2%). Among them, the causality was rated as 'possible' in 3 patients. Overall the tolerability was assessed as good or very good by 96.8% of the patients (Birch 100.0%, Tree-Mix 96.1%) and 97.1% by the investigators (Birch 98.1%, Tree-Mix 96.6%).

Conclusion: A SCIT product with an optimised allergen/adjuvant ratio (AVANZ) routinely used in the daily practise with 5 injections up-dosing was evaluated by patients and physicians to be effective and well tolerated.